Unionicola (Majumderatax) srilankana

Pešić, Vladimir & Zawal, Andrzej, 2018, A new species in the water mite subgenus Majumderatax Vidrine, 1993 from Sri Lanka (Acari: Hydrachnidia), Zootaxa 4457 (2), pp. 346-350: 346-349

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Unionicola (Majumderatax) srilankana

sp. nov.

Unionicola (Majumderatax) srilankana  sp. nov. ( Figs. 1–3View FIGURE 1View FIGURE 2View FIGURE 3)

Type material. Holotype female ( RMNHAbout RMNH), dissected and slide mounted, Sri Lanka, Mahaweli River E of Gallella; slow water flow, width 15 m, depth 0.5 m, sandy bottom with organic matter, Eichhornia crassipes  on water surface, 7°54'35.6"N, 81°06'15.2"EGoogleMaps  , 39 m asl., 2.i.2017, leg. A. Zawal. Paratypes: one male, one deutonymph, same data as holotype, dissected and slide mounted ( RMNHAbout RMNH)GoogleMaps  .

Diagnosis. Dorsum with a two pairs of muscle attachment platelets; P-4 with a serrated hyaline margin and two proximal projections on ventral margin; in the female anterior pair of genital plates medially with a cone-shaped extension bearing three peg-like setae. Cx-II and -III with hook-like extensions.

Description. General features (Adults). Dorsum with two pairs of muscle attachment platelets, anterior platelet elongated and close to each other, medial to Dgl-1, posterior platelet further apart, posteromedial to Dgl-2, knob-shaped ( Fig. 1A View Figure ). Coxae with a reticulate pattern, Cx-II laterally with two hook-like extensions, Cx-III laterally with two hooklike extensions. Cx-IV each with a short posterior apodeme ( Fig. 1B View Figure ) and a laterally directed extension. I-L-5 distally with three strong setae, two short stout setae located at distal margin and one larger and blade-like ( Fig. 1E View Figure ). Palp: P-2 medially with two short serrate setae; P-4 with a hyaline serrated ventral margin and with a small seta and two proximal projections on ventral margin, one distal bearing a peg-like seta; P-5 claw bifurcated into two very long, slender clawlets ( Fig. 1C View Figure ). Legs: number of swimming setae: III-L-4, 3; III-L-5, 3; IV-L-4, 3; IV-L-5, 3.

Female (holotype). Idiosoma L 590, W 465. Genital field with paired anterior wing-shaped plates, two acetabula and medially a cone-shaped extension bearing three peg like setae, posterior plates with three acetabula in triangular arrangement ( Fig. 1G View Figure ). Palp: total L 412, dL/H, dL/H ratio: P-1, 19/55, 0.34; P-2, 128/80, 1.6; P-3, 42/71, 0.59; P-4, 159/ 44, 3.6; P-5, 64/36, 1.79; L P-2/P-4 ratio 0.81. Gnathosoma L 188, W 103; L chelicera 152, cheliceral claw 89. Legs: dL of I-L-4-6: 100, 89, 109; L of I-L-5 blade-like distoventral seta 63; dL of IV-L: 73, 92, 108, 145, 172, 145.

Male (paratype). Idiosoma L 460. Genital field (L/W 80/131) with acetabula grouped, two anteriorly and three posteriorly and with a few small setae scattered over the genital plates ( Fig. 2A View Figure ): Palp ( Fig. 2B View Figure ): total L 374, dL/H, dL/H ratio: P-1, 16/47, 0.33; P-2, 103/69, 1.49; P-3, 39/58, 0.68; P-4, 144/43, 3.3; P-5, 72/30, 2.4; L P-2/P-4 ratio 0.72. Legs: dL of I-L-4-6: 88, 86, 88; L of I-L-5 blade-like distoventral seta ( Fig. 2C View Figure ) 55; dL of IV-L-4-6: 109, 152, 161.

Deutonymph. Idiosoma L 331. Dorsum with one pair of muscle attachment platelet. Provisional genital field with two pairs of acetabula ( Fig. 3A View Figure ). Palp: total L 268, dL/H, dL/H ratio: P-1, 12/36, 0.33; P-2, 73/39, 1.88; P-3, 28/38, 0.75; P-4, 102/36, 2.83; P-5, 53/22, 2.43; L P-2/P-4 ratio 0.72; P-2 with one medial serrate seta ( Fig. 3B View Figure ). Legs: dL of I-L: 34, 39, 56, 58, 57, 78; L of I-L-5 blade-like distoventral seta 50; dL of IV-L: 39, 47, 59, 84, 103, 116; number of swimming setae: III-L-4, 2; III-L-5, 2; IV-L-4, 2; IV-L-5, 2.

Etymology. The new species is named after its occurrence on Sri Lanka.

Remarks. The combination of P-4 with a hyaline serrated ventral margin bearing a small seta and the two medial serrate setae on P-2 makes the new species from Sri Lanka most similar to Unionicola grandiseta Savatenalinton & Smit, 2017  described on the basis of two females from Thailand ( Savatenalinton & Smit 2017). The female of latter species can easily be distinguished from Unionicola srilankana  sp. nov. in having one pair of platelet on the dorsum, one small ventral seta located behind the hyaline serrated margin of P-4, and with one peg-like seta only on the anterior genital plate.

Distribution. Sri Lanka; known only from the type locality.


National Museum of Natural History, Naturalis